Sirius was a star system in the Alpha Quadrant. Located less than 20 light years from Sol, this system consisted of binary companion stars, Sirius A and Sirius B. This system had at least nine planets, including Sirius IX.
The location of Sirius in the Milky Way Galaxy was depicted on a Federation star chart in 2293. (TAS: "Mudd's Passion"; Star Trek VI: The Undiscovered Country, production art; TNG: "The Naked Now", display graphic)
In 2364, on several occasions that year, viewscreen readouts aboard the USS Enterprise-D showed the location of Sirius A and B stars, in the form of charts from the Enterprise library computer. (TNG: "The Naked Now", "The Last Outpost", "Conspiracy")
The Sirius group was mentioned in Gene Roddenberry's original Star Trek pitch in one of the suggested story lines. In the storyline "Kentucky, Kentucky," the Sirius group was home to an Earth colony for fifty years. This colony was attacked by viking-like savages and reduced to a "frontier" log-fort life. They were regrouped and led by Captain Robert April when the SS Yorktown visited the colony.
The star chart that showed Earth commercial and exploration routes after the use of warp drive began. Sirius A was a destination on an exploration route. The chart was originally a drawing by Rick Sternbach that had been previously published in 1979 on page 77. In the "The Explored Galaxy" star chart, Sirius was located between the Tholian Assembly and Romulus. Both were identified in DS9: "Call to Arms" as being located in the Alpha Quadrant.
According to Star Trek: Star Charts (pg. 45), Sirius, also known as Alpha Canaris Majoris, was located in or near Federation space, in the Beta Quadrant. It was a binary star system. Sirius A was an A-class star with a magnitude was +1, which was a hundred times brighter than Sol. Sirius B was also an A-class star.